Electronic display devices are commonly used today in many applications including portable highway safety signs, billboards, scoreboards and other informational displays. These display devices consist of multiple rows of individual display elements which constitute controllable pixels in a visual matrix display. Predetermined patterns of display elements can be programmed to create any desired message, design or image.
The prior art is replete with numerous disclosures of electronic display devices. For example, one such display element employed with such devices includes an opaque panel having an aperture provided therein, and an associated flap which is pivotable from a first position covering the aperture, to a second position uncovering the aperture. The side of the flap which faces an observer when the aperture is covered has a substantially nonreflective surface. The other side of the flap which faces the observer when the flap is uncovered has a highly reflective surface. Accordingly, when the flap is open, light is emitted. Further, ambient light is reflected from the flap towards the observer.
The electronic display element identified above typically has a translucent lens covering an associated aperture. Still further, U.S. Pat. No. 5,111,193 to Huber, et al., describes an electronic display element having a translucent lens in a panel aperture and a pivotable flap which covers and exposes the lens. The reference to Huber is incorporated by reference herein.
While the devices identified above have operated with varying degrees of success, there are shortcomings in each of the devices which have detracted from their usefulness under certain operational and environmental conditions. For example, under conditions of poor visibility, such as what might be experienced in heavy fog, rain, snow and the like, these same signs may not be as readily visibly discernable as under normal viewing conditions. It would be desirable, therefore, to provide an improved pixel for use in a visual matrix display and which has improved visibility under poor viewing conditions such as described above.
Still other shortcoming with the prior art devices have been a result of characteristics inherent in their overall design. For example, the prior art has disclosed the use of individual energizable lamps which are disposed in light emitting relation relative to the respective pixels. The individual lamps are energized and deenergized by a programmable controller. As would be expected, the maintenance of these individual lamps is often time consuming, and difficult in view of the remote locations where these devices are often employed. Still another shortcoming with the devices described in the prior art references relates to the operational modes of the pixels. For example, most of the prior art devices have only two specific modes of operation, that is, the pixel is either in an operational condition (on) or a nonoperational condition (off). It would be highly desirable therefore, to provide a pixel which has more than one mode of operation thereby providing increased design options for a programmer of such devices.
The present invention provides several forms of an improved pixel for a visual matrix display which effectively transmits light provided to the pixel from various light sources. The pixel of the present invention further reflects light originating from sources in front of the visual matrix display thereby providing a visual matrix display which remains visibly discernable notwithstanding the deenergized state of an associated light source.